1. Field of the Invention
The present invention relates to a light emitting device module including a semiconductor device such as a semiconductor laser amplifier (SLA), which outputs light having a predetermined wavelength, and a method of making the same.
2. Related Background Art
A known example of the conventional light emitting device module comprises, as shown in FIG. 1, a semiconductor laser amplifier (SLA) A, which serves as a light emitting source, and an optical fiber B with a grating, which is a waveguide. In the SLA A, an active layer D is formed between cladding layers C, whereas a light exit facet E and a light reflecting facet F are respectively arranged at both end facets of the active layer D. The light exit facet E has a low light reflectivity, and the light reflecting facet F has a high light reflectivity. The optical fiber B is arranged such that its end facet faces the light exit facet E of the SLA A. In its core G, a diffraction grating H is a region such that the refractive index periodically changes along the longitudinal direction of the core G. The diffraction grating H and the light reflecting facet F constitute a resonator for laser oscillation. Here, the optical fiber comprises a core having a predetermined refractive index and a cladding, provided around the outer periphery of the core, having a refractive index lower than that of the core, and a grating in the core. The grating reflects light with a predetermined wavelength (referred to as "reflection wavelength of the grating" hereinafter). A method of making the grating is disclosed, for example, in International Publication No. WO 86/01303. In such a light emitting device module, light is generated in the active layer D when an electric current is injected into the SLA A. This light travels to-and-fro between the light reflecting facet F and the diffraction grating H of the optical fiber B as being reflected, so as to be amplified, thereby a laser beam I having a single wavelength (reflection wavelength of the grating) determined by the pitch of the diffraction grating H is outputted through the optical fiber B.